> ## Documentation Index
> Fetch the complete documentation index at: https://help.onetsolutions.net/llms.txt
> Use this file to discover all available pages before exploring further.

# [Instance Domains] Attach a domain to an instance

> Write the records the chosen profile describes into the domain's DNS zone and link the domain to this instance. Preview the plan first: this overwrites any record the profile covers. Re-sending with another profile updates the link and its records.



## OpenAPI

````yaml https://api.onetsolutions.net/schema post /v1/organizations/{organization_id}/projects/{project_id}/compute/instances/{instance_id}/domains
openapi: 3.0.3
info:
  title: OnetSolutions API
  version: v1 (v1)
  description: >

    ## Overview


    The OnetSolutions API provides programmatic access to manage your cloud
    infrastructure, domains, and web hosting services.


    ## Authentication


    All API requests require authentication using one of the following methods:


    - **JWT Token**: Obtain a token via login endpoints and include it in the
    `Authorization: Bearer <token>` header

    - **API Key**: Generate an API key from your account settings and use it as
    `Authorization: Bearer sk-onetsolutions-...`


    ## Rate Limiting


    API requests are rate-limited to ensure fair usage:

    - **Standard**: 1000 requests per minute

    - **Burst**: 100 requests per second


    ## Pagination


    List endpoints return paginated results. Use `page` and `page_size` query
    parameters.


    ## Error Handling


    The API uses standard HTTP status codes:

    - `200` Success

    - `201` Created

    - `400` Bad Request

    - `401` Unauthorized

    - `403` Forbidden

    - `404` Not Found

    - `429` Too Many Requests
servers:
  - url: https://api.onetsolutions.net
    description: Production
security: []
tags:
  - name: Authentication
    description: >-
      Login, passwordless authentication, MFA, OAuth providers, and token
      management.
  - name: Organizations
    description: >-
      Organization management, members, roles, modules, audit logs, and
      notification settings.
  - name: Projects
    description: Project management, team members, and project-scoped resources.
  - name: Compute
    description: >-
      Cloud instances, volumes, snapshots, backups, VPCs, firewalls, SSH keys,
      uptime monitors, and instance tasks.
  - name: Billing
    description: >-
      Shopping cart, orders, invoices, payments, payment methods, gateways,
      promo codes, and balance management.
  - name: Domains
    description: >-
      Domain availability, registration, transfers, DNS zones, DNS records, and
      TLD information.
  - name: Web Hosting
    description: >-
      cPanel-based web hosting, emails, databases, subdomains, FTP accounts,
      addon domains, and SSL certificates.
paths:
  /v1/organizations/{organization_id}/projects/{project_id}/compute/instances/{instance_id}/domains:
    post:
      tags:
        - Domains
      summary: '[Instance Domains] Attach a domain to an instance'
      description: >-
        Write the records the chosen profile describes into the domain's DNS
        zone and link the domain to this instance. Preview the plan first: this
        overwrites any record the profile covers. Re-sending with another
        profile updates the link and its records.
      operationId: attach_instance_domain
      parameters:
        - in: path
          name: instance_id
          schema:
            type: string
            format: uuid
          required: true
        - in: path
          name: organization_id
          schema:
            type: string
            format: uuid
          required: true
        - in: path
          name: project_id
          schema:
            type: string
            format: uuid
          required: true
      requestBody:
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/InstanceDomainRequest'
        required: true
      responses:
        '201':
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/InstanceDomain'
          description: The domain is attached and its records are written
        '400':
          description: >-
            The domain is not active, already points at another instance,
            belongs to another organization, or has no DNS zone hosted here
        '401':
          description: Authentication credentials were not provided or are invalid
        '403':
          description: You do not have permission to manage instances in this organization
        '404':
          description: Instance or domain not found in this organization and project
      security:
        - BearerAuth: []
components:
  schemas:
    InstanceDomainRequest:
      type: object
      properties:
        domain_id:
          type: string
          format: uuid
        profile:
          enum:
            - web
            - web_and_mail
            - cloudron
          type: string
          description: |-
            * `web` - web
            * `web_and_mail` - web_and_mail
            * `cloudron` - cloudron
          x-spec-enum-id: 93ac2bd3f07cdd6f
      required:
        - domain_id
        - profile
    InstanceDomain:
      type: object
      properties:
        id:
          type: string
          format: uuid
          readOnly: true
        domain_id:
          type: string
          format: uuid
          readOnly: true
        domain_name:
          type: string
          readOnly: true
        profile:
          type: string
          readOnly: true
        reverse_dns_applied:
          type: boolean
          readOnly: true
        created:
          type: string
          format: date-time
          readOnly: true
        modified:
          type: string
          format: date-time
          readOnly: true
      required:
        - created
        - domain_id
        - domain_name
        - id
        - modified
        - profile
        - reverse_dns_applied
  securitySchemes:
    BearerAuth:
      type: http
      scheme: bearer
      bearerFormat: JWT or API Key
      description: >-
        Use `Authorization: Bearer <token>` header. Token can be a JWT token or
        an API key (format: `sk-onetsolutions-...`).

````